This invention relates to growth inhibitors against algae and moss. In hydroponic culture of plants in a greenhouse environment, a growth of algae and moss is usually observed in the nutrient solution itself or on the machines and devices which come into contact with the nutrient solution. Such algae and moss tend to clog these machines and devices, preventing the nutrient solution from being circulated smoothly. When saplings of a plant such as lawn are grown, too, algae and moss are often seen to grow in the soil or on their supports. Such algae and moss not only adversely affect the external appearance of the plants but also cause a bad odor. The present invention relates to chemicals which are capable of inhibiting the growth of such undesirable algae and moss.
Copper sulfate, hydrated lime, agricultural chemicals and quaternary ammonium compounds have been known as growth inhibitors against algae and moss, and it has also been known that indoleacetic acid and 3-indole propionic acid have some functions of inhibiting the growth of algae and moss. Copper sulfate and hydrated lime, however, are harmful to the plants themselves, although this depends on the amount to be used, while agricultural chemicals and quaternary ammonium compounds tend to be harmful to the user as well as to the environment. As for indoleacetic acid and 3-indole propionic acid, they are not significantly effective as a growth inhibitor.
It is therefore an object of this invention to provide chemicals which are not harmful to plants themselves, have not harmful effects on workers and the environment but are capable of sufficiently inhibiting the growth of algae and moss even if only a small amount is used.
The invention is based on the discovery by the present inventors as a result of their diligent investigations in view of such an object that 3-(3-indolyl) butyric acid and its salts are appropriate growth inhibitors against algae and moss.